It may just be coincidence but every 1200 miles (I'm at just about 2400) the engine has a misfire episode. I'm going to bring it in to the dealership as soon as I can, which is Friday unfortunately. But has anybody with the SS/TC has this problem? It's the 4th cylinder again. The OnStar tech told me there is a chance it's nothing, or there's a chance there is some kind of dirt/contaminate in the fuel rail/injector.... joy. He said it would damage the catalytic converter.